1. Field of the Invention
The present invention relates to a cutting device for cutting a lengthy material, such as heat-sensitive, roll-type paper and photosensitive roll-type paper, to a desired length. Such paper is often used in business machines such as a facsimile device or a printer.
2. Description of Related Art
As shown in U.S. Pat. No. 3,918,339 to Cailloux, a conventional cutting device comprises a movable blade having a rectilinear cutting edge, which is rotated around a rotatable shaft and inclined at a predetermined angle to a surface of a sheet to be fed, and a stationary blade having a rectilinear cutting edge and provided substantially parallel to the surface of the sheet to be fed. When the movable blade is rotated around its shaft, the point where the movable blade contacts the stationary blade moves laterally from the cutting start position to the cutting end position. Thus, a roll-type paper inserted between the movable blade and the stationary blade is cut to a desired length.
Also, another conventional cutting device comprises a movable blade having a rectilinear cutting edge, a receiving blade having a rectilinear cutting edge and pivotably provided around a rotatable shaft and a spring for biasing the receiving blade towards the movable blade. The receiving blade rotatable shaft is substantially parallel to the surface of the sheet. Thus, any undesirable warp or curve resulting from the manufacturing process of the blades is compensated for.
In the above conventional cutting devices, if enough cutting power is provided to the device, any material can be surely cut in spite of the shape of the cutting edge. However, the cutting power (drive torque) available to the cutting device is limited. Therefore, in actual cutting devices, a cutting step during the manufacturing process of the blades, such as a milling cutting, is performed on the cutting edges of both the movable blade and the receiving blade, or to either one of the blades. Thus, one or both edges are sharpened and the contacting area of the edges and the paper inserted therein is reduced. Thereby, the cutting power generated when the paper is cut is enlarged, and the drive torque necessary for such cutting is reduced.
If the cutting step is performed to the cutting edges of both blades, it is necessary to repeat the sheet cutting movement several times without inserting the sheet between the cutting blades, after the blades are assembled as a cutting device. Thereby, a fragile part of each cutting edge which is formed during the cutting step is removed and the cutting edges fit together smoothly. As a result, a smooth cutting movement can be obtained.
However, in the cutting device having such the movable blade and the receiving blade, as mentioned above, it is necessary to perform the cutting step for the manufactured blade, and further the running-in step in which the sheet cutting movement is repeated several times without inserting the paper between the cutting blades. Therefore, the manufacturing cost of the cutting blade is high, and the manufacturing process is complicated and wastes much time.